From: Matt Birkholz <puck@birchwood-abbey.net>
Date: Sat, 26 Apr 2014 04:10:43 +0000 (-0700)
Subject: Fix BIGNUM_REDUCE_LENGTH to hide the unused (non-marked) words.
X-Git-Tag: release-9.2.0~18
X-Git-Url: https://birchwood-abbey.net/git?a=commitdiff_plain;h=750e3928ae1711e563658712e35a71f03fcb4429;p=mit-scheme.git

Fix BIGNUM_REDUCE_LENGTH to hide the unused (non-marked) words.

This quiets 7093 of the 7110 complaints from verify_heap during the
tests.
---

diff --git a/src/microcode/bignmint.h b/src/microcode/bignmint.h
index 7700259c5..e644716b0 100644
--- a/src/microcode/bignmint.h
+++ b/src/microcode/bignmint.h
@@ -56,8 +56,18 @@ typedef long bignum_length_type;
    space when a bignum's length is reduced from its original value. */
 #define BIGNUM_REDUCE_LENGTH(target, source, length)			\
 {									\
-  SET_VECTOR_LENGTH ((source), (BIGNUM_LENGTH_TO_GC_LENGTH (length)));	\
-  (target) = (source);							\
+  int new_gc_length = BIGNUM_LENGTH_TO_GC_LENGTH (length);		\
+  int old_gc_length = VECTOR_LENGTH (source);				\
+  int delta = old_gc_length - new_gc_length;				\
+  assert (delta >= 0);							\
+  assert ((target) == (source));					\
+  if (delta == 1)							\
+    VECTOR_SET (source, new_gc_length, SHARP_F);			\
+  else if (delta > 1)							\
+    VECTOR_SET (source, new_gc_length,					\
+		(MAKE_OBJECT (TC_MANIFEST_NM_VECTOR, delta - 1)));	\
+  if (delta != 0)							\
+    SET_VECTOR_LENGTH (source, new_gc_length);				\
 }
 
 #define BIGNUM_LENGTH_TO_GC_LENGTH(length)				\